Patch tracker / KB5002820
KB5002820: Office Online Server Security Update (December 2025)
KB5002820 is a High security update for Office Online Server, released 2025-12-09. It closes 6 CVEs with a maximum CVSS of 7.8. It is the 39th largest of the 59 updates Microsoft shipped that month, by CVEs closed.
Update summary
Fixes 6 CVEs. Most severe CVSS 7.8 (High). EPSS exploit probability up to <1%. Among the lower half of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Office Online Server has shipped since this one: KB5002884 (2026-08-11). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.
KB5002820 is the December 2025 patch bundle for Office 2019 (both 32-bit and 64-bit) and Office Online Server, resolving six CVEs with a top rating of High Severity (CVSS 7.8). The affected products span both desktop Office installs and the server-side Office Online Server component, so exposure includes end-user workstations and any on-premises document viewing infrastructure. None of these six CVEs are in the CISA KEV catalog or tied to ransomware, and EPSS peaks at only 1 percent, so this is a routine but broad patch rather than an emergency.
Do this: Deploy KB5002820 through your normal Office update ring, and separately confirm any Office Online Server hosts are patched since they update outside the desktop channel.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5002820
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5002820
- Released
- 2025-12-09
- Last changed
- 2026-07-08
- Changes tracked
- 2
Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.
Check if KB5002820 is installed
Elevated PowerShell. No output means it is not installed.
CVEs fixed by this update
Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.
| CVE | Severity | CVSS | EPSS | Exploited |
|---|---|---|---|---|
| CVE-2025-62553 | High | 7.8 | <1% | No |
| CVE-2025-62556 | High | 7.8 | <1% | No |
| CVE-2025-62560 | High | 7.8 | <1% | No |
| CVE-2025-62561 | High | 7.8 | <1% | No |
| CVE-2025-62563 | High | 7.8 | <1% | No |
| CVE-2025-62564 | High | 7.8 | <1% | No |
Scope and sources
- Affected products
- Also released in December 2025
KB5066586
98 CVEs · Critical · exploitedKB5066780
114 CVEs · Critical · exploitedKB5066782
103 CVEs · Critical · exploitedKB5066791
98 CVEs · Critical · exploitedKB5066793
108 CVEs · Critical · exploitedKB5066835
134 CVEs · Critical · exploitedKB5068779
32 CVEs · Critical · exploitedKB5068781
33 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.